Re: xfstests 073 regression

Wu Fengguang
2011-08-02T12:06:03Z

On Tue, Aug 02, 2011 at 07:44:28PM +0800, Wu Fengguang wrote:
> On Tue, Aug 02, 2011 at 12:52:42AM +0800, Christoph Hellwig wrote:
> > wb_check_background_flush is indeed what we're hitting.
>
> That means s_umount is NOT held by another queued writeback work.
>
> > See the trace output using a patch inspired by Curt's below:
> >
> > # tracer: nop
> > #
> > # TASK-PID CPU# TIMESTAMP FUNCTION
> > # | | | | |
> > <...>-4279 [000] 113.034052: writeback_grab_super_failed: bdi 7:0: sb_dev 0:0 nr_pages=9223372036854775807 sync_mode=0 kupdate=0 range_cyclic=1 background=1 reason=wb_check_background_flush
> > <...>-4279 [000] 113.034052: writeback_grab_super_failed: bdi 7:0: sb_dev 0:0 nr_pages=9223372036854775807 sync_mode=0 kupdate=0 range_cyclic=1 background=1 reason=wb_check_background_flush
> > <...>-4279 [000] 113.034052: writeback_grab_super_failed: bdi 7:0: sb_dev 0:0 nr_pages=9223372036854775807 sync_mode=0 kupdate=0 range_cyclic=1 background=1 reason=wb_check_background_flush
>
> What's that bdi 7:0? And sb_dev=0:0, nr_pages=9223372036854775807=0x7fffffffffffffff.
>
> All are indicating some special bdi/inode.

I see, it's loop0:

lrwxrwxrwx 1 root root 0 Aug 2 20:46 /sys/class/block/loop0/bdi -> ../../bdi/7:0

Thanks,
Fengguang